I’ve recently read two discussions — one by philologist Edward M. Cook (of Ralph the Sacred River), and one by Christian apologist Peter Kreeft — of what is being called the Argument from Desire. Then, by a strange coincidence, John C. Wright also came out with a post about it while I was in the process of composing this one.

The argument, though not the name, comes from C. S. Lewis, who summarizes it as follows in the tenth chapter of Mere Christianity:

Creatures are not born with desires unless satisfaction for these desires exists. A baby feels hunger; well, there is such a thing as food. A duckling wants to swim; well, there is such a thing as water. Men feel sexual desire; well, there is such a thing as sex. If I find in myself a desire which no experience in this world can satisfy, the most probable explanation is that I was made for another world.

This is not strictly speaking an argument for the existence of God, but for an undefined something which is beyond all known human experience. As Kreeft puts it, “What it proves is an unknown X, but an unknown whose direction, so to speak, is known. This X is more: more beauty, more desirability, more awesomeness, more joy.” Still, if even this much can be proved — if we have reason to believe in something beyond this world which is nevertheless intimately connected with human desires and interests — it gives us at least a starting point from which to theologize.

Of course no one would argue that every human desire — including my desire for an ansible and a cloak of invisibility — implies the existence of an object that would satisfy it, only that we are not born with vain desires. Lewis’s argument only applies to natural, innate, instinctive desires, so the first question that arises is how to distinguish these from artificial ones. Kreeft proposes the following criteria:

We generally “recognize corresponding states of deprivation” for natural desires, but not for artificial ones. “There is no word like ‘Ozlessness’ parallel to ‘sleeplessness.'”

Because natural desires come from our shared human nature, they “are found in all of us, but the artificial ones vary from person to person.”

Kreeft’s first point seems not to favor Lewis, who was so far from seeing his unsatisfied desire as a state of deprivation analogous to sleeplessness that he actually dubbed it “Joy” — not the desire for Joy, mind you, but Joy itself. As far as Lewis was concerned, his desire was not for Joy; it was Joy. The desire was itself intensely desirable. In that respect it seems more like an artificial, fanciful desire than a natural, biological one. Are intense hunger, loneliness, sleep deprivation, and so on ever joyous experiences? Wouldn’t it be odd if they were? Fantasizing about the land of Oz, on the other hand, can be rather pleasant.

The second point is also problematic, since so many obviously fanciful desires are nevertheless near-universal. As Wright (who, despite his Lewisian sympathies, finds this particular argument weak) puts it, “Who has not longed to fly to the stars . . . to speak to the trees and rivers and hills, . . . or peer into the thoughts of another, or live his life?” And who has not felt Lewisian Joy, the “desire which no experience in this world can satisfy,” a persistent longing which is no less intense for being vague? All of these must be in some sense “natural,” since they come so naturally to us, but it hardly follows that there must exist something which can satisfy them.

Desires, after all, do not exist to be satisfied; they exist to motivate behavior. Often the behavior elicited by a desire will result in its satisfaction (e.g., hunger motivates eating, and eating satisfies hunger) but this need not always be the case. Take for example the proverbial method of motivating a donkey to move by dangling a carrot in front of it, where the donkey’s desire serves its purpose (making the donkey move) even if it is never satisfied. In fact, the minute you actually let the donkey eat the carrot, it will stop walking and the purpose of the desire will be frustrated. You should only let it eat the carrot after you have reached your destination and no longer want the donkey to move; if you want it to keep moving indefinitely, you should never let it eat the carrot. Creating a desire serves to make the donkey move; satisfying the desire serves to make it stop. (Of course this is a highly artificial example, but in principle there’s nothing to stop nature from doing something similar.) So in thinking about desire and satisfaction, we need to keep in mind two important points — important enough to be bulleted:

To understand why a given natural desire exists, the correct question to ask is not what would satisfy it, but what evolutionarily useful behavior it serves to motivate.

Other things being equal, we should expect a desire to be satisfied only when, and only for so long as, the behavior it serves to motivate is no longer useful.

If there were some behavior which it were evolutionarily beneficial for us to perform only once, or only a specific finite number of times, then we could expect to find a natural desire which could be satisfied in the fullest sense of that word — we reach the intended goal, the desire is completely and permanently quenched, and we move on to other things. Mission accomplished. It’s hard to think of any clear examples of this in the real world, though, which is perhaps only to be expected. The evolutionary project — ensuring that copies of as many of our genes as possible continue to exist for as long as possible — is inherently open-ended, a race with no finish line, and we might expect a similar open-endedness in the desires which were created to serve it.

More typically we find that our natural desires can be satisfied, but only for a time. The satisfaction is temporary, and the desire is quenched and rekindled, quenched and rekindled, in a cycle that can continue indefinitely. We eat, we drink, we sleep — but hunger, thirst, and fatigue are never banished for long. All the rivers run into the sea, yet the sea is not full. This is a confusing state of affairs if we see satisfaction as being the purpose of desire, but it makes perfect sense if we keep in mind that desires exist to trigger behavior and satisfaction exists to turn it off. When the body needs fuel, the desire to eat is turned on; when it has enough, and eating more would actually be detrimental, the desire is turned off — satisfied — but only until fuel supplies begin to run low again.

The on-again off-again nature of hunger is explained by the fact that eating regularly is evolutionarily useful but eating until you burst is not. But what if there were a behavior which, unlike eating, was always useful and never needed to be turned off? Well, in that case we would expect that behavior to be motivated by a desire which could never be satisfied. The most obvious example of this in nature is our desire for life itself. Nature has given most of us an insatiable desire to go on living indefinitely, not because immortality is actually on offer, but to motivate us to extend our finite lives for as long as we possibly can. Other ways of coping with our unacceptable mortality — having children, trying to bequeath something of lasting value to posterity, and so on — also tend to serve evolution’s ends. So long as we keep chasing the carrot of eternal life, pulling our wagonload of selfish genes behind us, the desire serves its purpose, even if satisfaction remains forever out of reach.

Lewisian Joy isn’t as straightforward as a desire for immortality — it’s a vague desire for a certain je ne sais quoi — and so the behavior it serves to motivate is less easily characterized. However, I suspect that it still does serve to motivate broadly predictable patterns of behavior. Someone who is motivated by Joy is likely to seek, as Kreeft puts it, “more awesomeness” — where our idea of awesomeness will tend to be drawn from our other, more straightforward (and more clearly evolutionarily useful) desires. The inchoate longing for “something more” is not as open-ended as it might seem, since our human nature will predictably direct it towards certain goals (such as power, wisdom, and beauty) rather than others (such as trying to ensure that the number of turnips in the world is prime). Given how clever our species is, and how good we are at finding ways to cheat evolution by satisfying our desires without reaching the goals for which those desires were created (see my post on the Genie scenario) — Joy may be a broadly effective way of keeping us from resting on unearned laurels.

I’m getting into just-so-story territory here, but all that’s really necessary to counter Lewis is to come up with an explanation for vague unsatisfiable desires which, however hypothetical and ad hoc it might be, is at least less far-fetched than his own “most probable explanation” — namely, that there must exist some “other world” than the known universe and that it was for this hypothetical world that we were “made.” And, that, I think, is a pretty easy standard to meet.

2 responses to “The Argument from Desire”

Perhaps you are only saying that the argument from desire does not work for you? It is not, of course, a proof.

It is a fact that any occurrence of any kind can be explained by a number of hypotheses; and any scientific theory can be picked-apart by looking at the pieces of evidence which ‘support’ it, piecemeal and one at a time, to generate as many ad hoc explanations as there are instances.

Or, no experiment or observation is ever conclusive – but always has limitations, always can be taken to imply a need for further observations and experiments, can be taken either as evidence or explained-away.

But the conclusion, at the end of this kind of process, is that there are no general theories at all, and we know nothing about anything. Nihilism.

A less responsible variant is to pick apart your opponent’s arguments, piecemeal and one at a time, showing that each can be explained-away – but never to do the same with one’s own favoured explanatory scheme: this is what happens in the mainstream public discourse with respect to IQ differences between groups. The favoured ‘hypothesis’ is that everything attributed to the unifying hypothesis of hereditary IQ can be (should be) explained by ‘environment’ (i.e. by 1001 ad hoc hypotheses which are united only in being non-genetic).

In attacking this argument legitimately, therefore, it must be made clear one is *comparing* two hypotheses, applying the same arguments to each. This is far from straightforward, because different hypotheses may have vastly different scope.

I think that here you are doing no more than show that the argument from desire is not conclusive, and in a context where you regard Lewis’s religious hypotheses as impossible; so you already ‘know’ in advance that this and every other argument depending upon the supernatural is wrong, and you merely need to find out in which particular way it is wrong.

Probably this is because you feel that the supernatural should only be regarded as possible if it is ‘needed’, if non-supernatural explanations fail – and you can find no situation in which the supernatural is needed to explain any particular thing.

But of course a world which includes the supernatural is very different from that which contains no supernatural, as has become clear now that we live in a public world that contains no supernatural.

In this sense there is indeed a need for the supernatural – or, at least, non-supernaturalist views have not *yet* been able to replace some vital aspects provided by supernaturalism.

(When I was an atheist I saw may main job in life as trying to discover this kind of replacement.)

What does “the supernatural” mean to you? I’ve never found it a useful category. As far as I can see, the question “Does the supernatural exist?” is empty, since whenever we find strong empirical evidence that a given thing exists, we no longer consider it supernatural (see magnetism, hypnosis, teleportation, parallel universes, etc.).

If Lewis had recast his argument in naturalistic terms — as evidence, say, that our species had evolved in a very different (but not “supernatural”) environment — I would still be against him, just as I am as much against Raelian creationists as Christian ones. I simply think his argument is based on an incorrect understanding of desire — that it exists to be satisfied, rather than to motivate behavior.